LRA Community:http://hdl.handle.net/2381/10
Tue, 03 Mar 2015 20:22:08 GMT2015-03-03T20:22:08ZFunctional analysis of novel genetic markers of coronary artery disease identified by genome-wide association studieshttp://hdl.handle.net/2381/31595
Title: Functional analysis of novel genetic markers of coronary artery disease identified by genome-wide association studies
Authors: Braund, Peter Stuart
Abstract: Coronary artery disease (CAD) is the commonest cause of death worldwide. It is a multifactorial disease caused by interplay between genes and environment. Defining genes that affect CAD risk and understanding their mechanisms may help to improve its prevention and treatment. Recent genome-wide association studies have identified several novel loci associated with CAD. In this thesis I examined two of these loci.
The first was a locus on chromosome 1p13.3. I showed that this locus was also associated with LDL-cholesterol. Fine-mapping of the locus and in silico analyses suggested that SNP rs12740374, where the risk allele disrupts binding of a liver-specific transcription factor, is probably the causal variant at the locus. Finally, I showed that the lipid-lowering effect of statin is independent of this locus, suggesting that targeting the mechanism by which this locus affects LDL-cholesterol may provide additional therapeutic benefit.
The second locus was on chromosome 13q34 located near the COL4A1 and COL4A2 genes which code for collagen Type 4, a key component of the arterial wall. In silico analyses identified an intronic 4-SNP haplotype within a bidirectional promoter that was likely to include the causal variant(s). A putative kidney expression QTL was identified with the CAD risk allele associated with lower expression of COL4A1 and COL4A2. Functional experiments showed DNA-protein binding to the SNPs in the haploblock. However, there were no differences in level of DNA-binding between the alleles or a differential impact on gene expression. In a clinical study, there was no difference between the 13q34 genotype groups in restenosis rates in patients undergoing percutaneous coronary angioplasty.
In conclusion, the work on locus 1p13.3 shows that it is possible to identify a causal SNP from a GWA study signal, and elucidate its mechanism, but the studies on locus 13q34, indicates that this is a challenging process.Wed, 04 Feb 2015 16:12:05 GMThttp://hdl.handle.net/2381/315952015-02-04T16:12:05ZType 2 Diabetes Mellitus and Impaired Glucose Regulation in a multi-ethnic populationhttp://hdl.handle.net/2381/31395
Title: Type 2 Diabetes Mellitus and Impaired Glucose Regulation in a multi-ethnic population
Authors: Mostafa, Samiul Adim
Abstract: The incidence of Type 2 Diabetes Mellitus (T2DM) is increasing rapidly, therefore there is a need to detect this disease earlier and more efficiently, and also to identify novel risk factors that may aid both its detection and prevention.
Aims: 1) To discuss the benefits and disadvantages of using HbA1c for diagnosis of T2DM and impaired glucose regulation (IGR).
2) To explore the impact on prevalence of using HbA1c to detect T2DM and IGR in global and local populations.
3) To determine if diagnostic cut-points are equivalent in different ethnic groups
4) To determine the use of the triglyceride-to-HDL ratio and its association with insulin resistance and whether statins and liver enzymes predict T2DM.
5) To investigate if Vitamin D deficiency has a role in the prevention of T2DM by designing a 6 month randomised controlled trial on vitamin D replacement.
Key findings: 1) Using HbA1c for diagnosis has some logistical advantages over glucose testing, but may not detect the same people as having T2DM or IGR.
2) In Leicestershire, using HbA1c will increase numbers of people with T2DM and IGR. On global level, there will be regional variation on the effect on prevalence.
3) HbA1c, fasting and two hour plasma glucose are independently higher in South Asians (SA). Complications of T2DM may begin earlier in SA.
4) The triglyceride-to-HDL ratio associates with insulin resistance in Europeans and SA men but not women. Statin therapy reduces the risk of incident T2DM. Liver enzymes predict T2DM in Europeans but not SA.
5) Vitamin D deficiency may form a target for reducing insulin resistance in SA – the final results of the VITALITY study in 2015 will contribute to evidence base in this area.
Conclusions: In this thesis I have explored new ways of detecting T2DM and IGR by using HbA1c and what impact this may have; also novel risk factors for T2DM have been investigated that may help improve methods of both earlier detection and prevention of T2DM.Thu, 08 Jan 2015 14:58:28 GMThttp://hdl.handle.net/2381/313952015-01-08T14:58:28ZInvestigation of the normal and pathological development of the macula of the infant human eye using high resolution Optical Coherence Tomography (OCT)http://hdl.handle.net/2381/31394
Title: Investigation of the normal and pathological development of the macula of the infant human eye using high resolution Optical Coherence Tomography (OCT)
Authors: Lee, Helena
Abstract: The fovea is a specialised retinal area responsible for high spatial vision.
Development of the fovea involves centrifugal migration of inner retinal layers (IRLs)
away from the fovea and centripetal displacement of the cone photoreceptors into the
fovea and is thought to be complete by 5 years of age. Current understanding of human
foveal development is limited to studies of few histological specimens. The recent
development of hand-held spectral domain optical coherence tomography (HHSDOCT),
can overcome this limitation by facilitating large scale in vivo imaging of the
infant human retina, both in controls and in conditions such as achromatopsia and
albinism, where foveal development is disrupted.
In this thesis, we optimise image acquisition and analysis with HH-SDOCT in
young children with nystagmus. We show that HH-SDOCT is reliable in children with
and without nystagmus, with an intraclass correlation coefficient of 0.96 for central
macular thickness measurements. The non-linear developmental trajectories of each
retinal layer modelled in a large cohort of 256 controls suggest that development
continues until 12 years of age. A paradigm for the etiological diagnosis of nystagmus
using OCT is presented.
We describe multiple abnormalities of retinal development in young children
with achromatopsia and albinism, including delayed regression of the IRLs from the
fovea, diminished elongation of the photoreceptor layers with age and a reduction in
perifoveal retinal thickness. This results in significantly increased IRL and decreased
photoreceptor thicknesses at the fovea in both conditions (p < 0.05). In contrast, the IRL
thickness is significantly decreased at the perifovea in both achromatopsia and albinism
(p < 0.01). There is evidence of postnatal development in the achromat and albino
retina. In achromatopsia, disruption of photoreceptors is progressive with age. With
gene therapy imminent, potentially earlier treatment of these conditions may normalise
retinal development and optimise vision.Thu, 08 Jan 2015 14:49:05 GMThttp://hdl.handle.net/2381/313942015-01-08T14:49:05ZNephrotoxicity of immunosuppressant drugs in salt-depletion and modification of effect by an antifibrotic agenthttp://hdl.handle.net/2381/29914
Title: Nephrotoxicity of immunosuppressant drugs in salt-depletion and modification of effect by an antifibrotic agent
Authors: Brook, Nicholas Roger
Abstract: The calcineurin inhibitors, cyclosporine and tacrolimus, are pivotal immunosuppressants in renal transplantation, but produce a cascade of acute (functional) and chronic (fibrotic) injurious events that contribute to chronic allograft nephropathy (CAN). Using the rat salt depletion model of calcineurin inhibitor toxicity, this study aimed to examine the effects of clinically relevant combinations of cyclosporine, tacrolimus and sirolimus on renal functional, structural and molecular markers of injury. Further, the effect of pirfenidone when added to these drug combinations was examined. There were differences in the effects of cyclosporine and tacrolimus on functional and molecular variables, with tacrolimus displaying more favourable results. As sole therapy, sirolimus had no effect on renal function or messenger RNA expression. Deterioration in renal function and a deleterious effect on molecular markers of fibrosis were seen when cyclosporine and sirolimus were combined at high doses; at lower doses, favourable outcomes for these end-points were elicited. When sirolimus and tacrolimus were combined, renal function worsened and the beneficial molecular effects of tacrolimus were reversed. Pirfenidone's actions were non-dose dependent and beneficial effects for renal function and molecular markers were demonstrated. The effect of pirfenidone on renal function has not previously been described. There were no differences in urinary protein or interstitial fibrosis measurements across the groups. Without fibrosis, it is impossible to say whether pirfenidone acted in a truly antifibrotic manner. However, the molecular changes possibly represent interim markers of fibrosis, suggesting such an effect may have been developing..Mon, 15 Dec 2014 10:34:31 GMThttp://hdl.handle.net/2381/299142014-12-15T10:34:31ZIschaemia/reperfusion injury and preconditioning in the human myocardium : the role of alpha 1 adrenoceptors and disease stateshttp://hdl.handle.net/2381/29913
Title: Ischaemia/reperfusion injury and preconditioning in the human myocardium : the role of alpha 1 adrenoceptors and disease states
Authors: Loubani, Mahmoud
Abstract: The present studies have demonstrated that alpha1 -adrenoceptors play an important role in the ischaemia/reoxygenation-induced injury of the human atrial myocardium. They have shown that stimulation of alpha1-adrenoceptors with phenylephrine protects against injury whereas their blockade with prazosin is detrimental, both effects obtained in a dose-dependent manner. They have also shown that the effect of the stimulation or blockade of alpha1-adrenoceptors depends on the time of administration so that 1-adrenoceptors' stimulation is protective when given prior to ischaemia but detrimental when giving during ischaemia. On the contrary, alpha1-adrenoceptors' blockade is beneficial during ischaemia, detrimental during reoxygenation but has no significant effect prior to ischaemia. It appears that similar maximal protection can be obtained with alpha1-stimulation prior to ischaemia and with alpha1-blockade during ischaemia although the combination of the two does not induce additional protection. Furthermore, the protective effect of alpha1-stimulation prior to ischaemia is as potent as ischaemic preconditioning (IP). In this thesis, I have also demonstrated that protection with pharmacological preconditioning by activation of alpha1-adrenoreceptors or adenosine receptors is identical to that of IP in the human myocardium.;These studies have provided novel information to understand the underlying mechanism of protection by preconditioning of the human myocardium. They have shown that mitoKATP channels, PKC and p38MAPK are an integral part of the cellular signal transduction involved in this cardioprotection in which mitoKATP channels are placed upstream and p38MAPK is placed downstream of PKC.;The abolition of the ability of the human myocardium to be protected by ischaemic and pharmacological preconditioning without exacerbating the susceptibility to ischaemic injury when nicorandil, a mitoKATP channel opener and nitric oxide donor, was administered clinically was unexpected. I demonstrated that the likely cause of the failure to precondition the myocardium of patients on nicrorandil is the unresponsiveness of the mitoKATP channels since protection cannot be obtained with diazoxide, a specific mitoKchannel opener, but can be elicited by activation of PKC and p38MAPK that are downstream of mitoKATP channels in the signalling transduction cascade of preconditioning.;The sulfonylureas glibenclamide and gliclazide, that block KATP channels, have distinctive effects on IP. Thus, although glibenclamide abolished the protective effect of preconditioning even at 0.1 muM, gliclazide did at a higher concentration 30muM. The cardioprotection induced by diazoxide, which open mitoKATP channels was also abrogated by glibenclamide. However glibenclamide did not block the protective effect of activation of PKC and p38MAPK.Mon, 15 Dec 2014 10:34:30 GMThttp://hdl.handle.net/2381/299132014-12-15T10:34:30ZGlucose and human vascular endothelial cell ageinghttp://hdl.handle.net/2381/29912
Title: Glucose and human vascular endothelial cell ageing
Authors: Verma, Raman.
Abstract: This study examined whether raised extracellular glucose concentrations (through increased oxidative stress) could induce DNA damage and hasten human vascular endothelial cell (HUVEC) senescence.;HUVEC DNA damage was measured using the comet assay. Senescence was detected by beta-Galactosidase staining at pH 6. Telomere lengths and mitochondrial genome copy numbers were obtained through Southern analysis. 8-oxoguanine excision was assessed by a nucleotide incision assay. Western blotting demonstrated Ref-1 and electron transport chain complex IV (subunit I) expression.;DNA damage peaked after four fours of high glucose (HG; 22mM) exposure. This was D-glucose specific and concentration dependent. DNA damage was attenuated by N-acetylcysteine (p < 0.01) and augmented by formamidopyrimidine DNA glycosylase (p <0.05), indicating that HG induced oxidative lesions. DNA damage was associated with premature HUVEC senescence (p = 0.011) and accelerated telomere shortening (p = 0.03). N-acetylcysteine did not prevent telomere attrition. 8-oxoguanine incision and Ref-1 expression decreased during 24-hour HG treatment, suggesting that HG could disrupt the efficiency of oxidative DNA lesion repair. No difference in mitochondrial DNA content in HG exposed HUVECs was found. However, complex IV (subunit I) expression fell in HG conditioned HUVECs ( p = 0.006), implying that HG could affect mitochondrial activity.;This study demonstrates for the first time that elevated glucose concentrations promote oxidative DNA damage in human vascular cells. This leads to accelerated telomere attrition, prompts premature human endothelial cell senescence and may profoundly disturb mitochondrial function. These observations provide a novel mechanism to implicate glucose in accelerated vascular ageing in diabetes.Mon, 15 Dec 2014 10:34:30 GMThttp://hdl.handle.net/2381/299122014-12-15T10:34:30ZCharacterisation and studies of T-lymphoblastoid procoagulant activityhttp://hdl.handle.net/2381/29911
Title: Characterisation and studies of T-lymphoblastoid procoagulant activity
Authors: Pickering, William Maxwell
Abstract: Coagulation is an interaction between tissue factor (TF) and clotting factors, assembled on a negatively-charged phospholipid surface. Previously it was reported that malignant T-lymphoblastoid cells might have the ability to support procoagulant activity (PCA). In the present study human T-cell lines (CEM-CCRF, Jurkat, Molt-4, A3.01) representing different stages of differentiation were cultured and their basal PCA compared with that of a monocytoid cell line (THP-1). Various phospholipid or TF-dependent coagulation tests were used to investigate this PCA. The effect of TF on the phospholipid-dependent assays was also investigated.;The phospholipid dependent PCA was reported as phospholipid units/mL by comparison with a bovine brain phospholipid standard. There was variation in the procoagulant activity between the cell lines. Using calcium ionophore to stimulate this activity, and annexin A5 and an inhibitory phosphatidylserine antibody (3G4) to inhibit it, along with flow cytometry data, it was concluded that this activity was due to the exposure of anionic phospholipid.;Two pathophysiological processes, apoptosis and lipid peroxidation significantly enhanced the PCA of T-Lymphoblastoid cells. This enhanced PCA was higher than that observed following calcium ionophore treatment, suggesting the increase in activity was not solely due to anionic phospholipid exposure. Whilst annexin A5FITC and 3G4 bound to cells undergoing apoptosis only annexin A5FITC bound to cells exposed to oxidative stress. This implies that apoptosis increases PCA by causing the translocation of oxidised/native phosphatidylserine to the outer membrane, whilst lipid peroxidation appears to increase the PCA possibly due to malondialdehyde-adducts altering the net charge on the cell surface, which allows phospholipids other than phosphatidylserine to participate in thrombin generation. The possible pathophysiological significance of these observations with regard to thromboembolic complications of leukaemia, chemotherapy and atherosclerosis is discussed.Mon, 15 Dec 2014 10:34:29 GMThttp://hdl.handle.net/2381/299112014-12-15T10:34:29ZOxidative stress and cardiovascular ageing in diabeteshttp://hdl.handle.net/2381/29910
Title: Oxidative stress and cardiovascular ageing in diabetes
Authors: Dewar, Mairead.
Abstract: Oxidative stress is thought to be elevated in diabetes as a consequence of hyperglycaemia. This thesis investigates oxidative DNA damage in diabetes, which may contribute to accelerated vascular ageing. Telomeric and mitochondrial DNA are two areas of the genome that may be more susceptible to oxidative stress and were therefore investigated.;51 patients with diabetes (aged 31-78 years) and 101 healthy controls (aged 19-75 years) were recruited. 51 of the controls were age- and sex-matched to be patient group. For both populations physiological profiles were obtained and pulse wave velocity (PWV), an index of vascular stiffness, was measured. Oxidative DNA damage was also investigated in peripheral blood using the comet assay, and in more depth by measuring terminal restriction fragment (TRF) lengths and quantifying mitochondrial DNA (mtDNA) content.;PWV increased with age in both study groups (p<0.001) and was significantly higher in the patient group (8.00 +/- 2.89 versus 7.29 +/- 1.64 m/s; p=0.006), suggesting accelerated vascular ageing in diabetes. This was accompanied by elevated levels of oxidative DNA damage; 25.81 +/- 1.18 versus 21.40 +/- 0.81% Tail DNA (p=0.003) in patients and controls respectively. TRF length inversely correlated with age in both groups (p<0.05), with similar rates of attrition, and although they were shorter in the patients with diabetes, this was not significant (p=0.10). Quantification of mtDNA revealed significantly lower levels in the patients with diabetes compared to the controls (0.014 versus 0.016; p=0.020).;There is accelerated vascular ageing in diabetes, which is accompanied by elevated oxidative DNA damage, and a decrease in mtDNA, but no alteration in TRF length compared to a healthy control population. The mechanisms underlying these alterations are unknown with the lack of correlations with glycaemic control suggesting it is not the sole cause but it may still contribute.Mon, 15 Dec 2014 10:34:29 GMThttp://hdl.handle.net/2381/299102014-12-15T10:34:29ZThe physical and functional mapping of a blood pressure quantitative trait locus on rat chromosome 1http://hdl.handle.net/2381/29909
Title: The physical and functional mapping of a blood pressure quantitative trait locus on rat chromosome 1
Authors: Clemitson, Jenny-Rebecca.
Abstract: The aim of the studies presented in this thesis was to investigate the blood pressure (BP) quantitative trait locus (QTL) identified on rat chromosome 1 in a cross of the spontaneously hypertensive rat (SHR) and Wistar Kyoto (WKY) rat, and isolated in reciprocal congenic strains derived from the SHR and WKY.;Complementary strategies were employed to define the mechanism of the BP QTL effect, refine its genomic location and identify strong candidate genes located within the relevant chromosomal region. A kidney transplantation experiment demonstrated that the BP effect of the QTL could be physically 'carried' over with the graft, as the normotensive WKY recipients of kidneys from the hypertensive WConSa congenic donors developed significantly higher BP. This result implies that the BP QTL mediates its BP via renal genetic factors. A gene profiling experiment was carried out using a specifically constructed cDNA microarray containing 615 probes from genes and expression sequence tags known to be located within the congenic region. Comparison of expression profiles of SHR, WKY and congenic strain kidneys identified 13 differentially expressed genes which may imply a role for renal sodium transport and fatty acid metabolism pathways in the BP effect of the QTL. An overlapping YAC and BAC contig map of the WConSa BP QTL region was produced, to provide a useful resource for filling in gaps not covered by the Rat Genome Sequence and identifying gene and DNA marker locations. New subcongenic strains derived from the Sisal congenic strain were constructed (Sisa3), using polymorphic markers tested and confirmed as residing within the QTL region. The Sisa3 strains refined the genomic location of the BP QTL from a 3-5cM area to a region half its original size and reduced the number of potential candidate genes to 30.Mon, 15 Dec 2014 10:34:28 GMThttp://hdl.handle.net/2381/299092014-12-15T10:34:28ZA feasibility and safety study of immediate blood pressure manipulation in acute post-stroke patientshttp://hdl.handle.net/2381/29908
Title: A feasibility and safety study of immediate blood pressure manipulation in acute post-stroke patients
Authors: Mistri, Amit K.
Abstract: This thesis examines the feasibility and safety of blood pressure (BP) lowering using labetalol or lisinopril, in acute ischaemic or haemorrhagic stroke within the confines of a randomised double-blind placebo-controlled trial.;A systematic review of pressor therapy in acute stroke identified pilot studies which have reported no harmful effects, and no randomised controlled trials. While pressor therapy was not investigated in this study, centres with established rapid admission protocols, availability of urgent computerized tomography and intensive monitoring facilities will be needed for such a study.;Elevated BP following acute stroke is associated with adverse prognosis. Whether BP lowering in this situation is beneficial or harmful is unknown. Active intervention in this study significantly reduced SBP during the first 24 hours and at two weeks, but not DBP, compared to placebo. No significant difference in short-term outcome (death and dependency at 2 weeks), or adverse events (including early neurological deterioration) was seen.;Sublingual lisinopril for dysphagic patients was as effective and well-tolerated as oral lisinopril. This is a novel method of administering anti-hypertensives in acute stroke, which could be administered at first contact with healthcare providers, and does not require intensive monitoring as with intravenous agents like labetalol.;Recruitment to the study was poor, primarily due to inadequate number of centres, fewer patients conforming to eligibility criteria than initially estimated, and delays in hospital admission. Analysis of screening data showed that only a small minority of patients with acute stroke were randomised to one of two stroke-BP studies (<9%). This will limit the applicability of results to the clinical scenario.;A definitive trial of BP lowering in acute stroke with adequate sample size is needed.Mon, 15 Dec 2014 10:34:27 GMThttp://hdl.handle.net/2381/299082014-12-15T10:34:27ZStudies into angiopoietin-1 and tie receptor signalling during endothelial responses to acute inflammationhttp://hdl.handle.net/2381/29907
Title: Studies into angiopoietin-1 and tie receptor signalling during endothelial responses to acute inflammation
Authors: Milner, Chris Stephen
Abstract: Endothelial dysfunction is a major component of the systemic inflammatory response syndrome (SIRS) triggered by major injury including burns. Angiopoietin-1, a key regulator of angiogenesis operates through two different receptors, Tie1 and Tie2. Identifying specific roles of each receptor in mediating the protective effects of Ang1 is essential for designing drug therapy for pathological inflammatory responses. In vitro models of endothelial permeability, survival and adhesion molecule expression have been established to study the effects of Ang-1 on Tie receptor deficient HUVEC generated by SiRNA techniques. Tie receptor knock-down was highly effective in HUVEC, and subsequent experiments using these cells proved the hypothesis that Tie2 is the principal receptor mediating Ang-1 induced endothelial survival and reduced endothelial permeability. In addition, absent Tie1 was found to increase baseline endothelial permeability and apoptosis in HUVEC, whilst the full anti-apoptotic effect of VEGF was shown to require both Tiel and Tie2, adding to other data indicating a novel form of heterodimeric transactivation between the two receptors. Using the developed cell adhesion molecule (CAM) assay, experiments using naive HUVEC quantitated the anti-inflammatory effects of Ang-1 following stimulation by key pro-inflammatory cytokines such as Il-1. Moreover, preliminary experiments using plasma from patients with SIRS demonstrated the usefulness of the inflammatory CAM assay as a model for studying endothelial inflammatory responses in humans. Finally, experiments combining SIRS plasma with Ang-1 demonstrated a possible role for Ang-1 in the inhibition of SIRS plasma induced CAM expression.Mon, 15 Dec 2014 10:34:26 GMThttp://hdl.handle.net/2381/299072014-12-15T10:34:26ZThe role of endothelial progenitor cell in the aetiology and pathogenesis of coronary artery diseasehttp://hdl.handle.net/2381/29905
Title: The role of endothelial progenitor cell in the aetiology and pathogenesis of coronary artery disease
Authors: Whittaker, Andrew
Abstract: The primary aims of the work undertaken in this thesis were to examine whether there is genetic regulation of EPC number and / or function and to determine if EPC dysfunction precedes the onset of CAD. In additional studies, the role that EPCs play in two relevant coronary pathologies - in-stent restenosis (ISR) and coronary collateralisation - was examined. Finally, an exploratory analysis was undertaken to determine if cellular senescence, assessed by telomere length, impacts on EPC function. A total of 162 subjects were studied including 24 healthy parent-healthy offspring pairs and 27 CAD parent-healthy offspring pairs for the principle objectives. The relationships between EPCs and ISR and coronary collateralisation were studied in 21 and 39 subjects, respectively. In all subjects, the number of circulating CD34+VEGFR-2+ and AC133+VEGFR-2+ EPCs, the number of EPCs grown in vitro, and the migration capacity of cultured EPCs towards VEGF were determined. There was significant correlation in the number of cultured EPCs between parents and their offspring (Healthy: R=0.492, p=0.015; CAD: R=0.751, p<0.001) Offspring of subjects with CAD had significantly higher numbers of circulating CD34+VEGFR-2+ and AC133+VEGFR-2+ cells than offspring of healthy subjects (p=0.018 and p<0.001, respectively). There was no striking relationship between EPC number or function and either ISR or degree of coronary collateralisation. Telomeres were significantly shorter in offspring of subjects with CAD than offspring of healthy subjects (5.7 +/- 0.2 kb vs 6.7 +/- 0.7 kb, p < 0.001). There was no association between telomere length and EPC function. EPC number is at least partly genetically regulated. Circulating EPC number may represent biological markers of occult vascular damage in offspring with hereditary risk of CAD.Mon, 15 Dec 2014 10:34:24 GMThttp://hdl.handle.net/2381/299052014-12-15T10:34:24ZThe role of ms1 in cardiac physiology and diseasehttp://hdl.handle.net/2381/29906
Title: The role of ms1 in cardiac physiology and disease
Authors: Koekemoer, Andrea Louise
Abstract: Previous work in the group identified a novel gene, designated myocyte stress 1 (ms1), which is up-regulated within 1 hour in the left ventricular following aortic banding in the rat, suggesting a possible role for ms1 in the initial signalling of the hypertrophic response. ms1 is also expressed during cardiac development and is transiently up-regulated during ischaemia-reperfusion in vitro. This suggests that ms1 may play a more widespread role in cardiac physiology.;The aim of the work in this thesis was to better understand the role of ms1 in cardiac physiology and disease through a combination of in vitro and in vivo approaches. It was demonstrated that transient over-expression of a c-Myc-ms1 fusion protein into a heart-derived rat cell line, H9c2, colocalised with actin and altered gene expression of known hypertrophic and cardioprotective markers that are target genes of the myocardin-related transcription factor (MRTF)/serum response factor (SRF) transcriptional pathway. The size of cells over-expressing ms1 significantly increased by 47% when compared to untransfected cells and over-expression of ms1 markedly inhibited staurosporine-induced apoptosis by 88%. A Cre/loxP system based construct was developed to assess the in vivo of increased ms1 expression and was confirmed to work in a cell-based system. However, two independent attempts to make a transgenic mouse over-expressing ms1 were unsuccessful despite successful integration of the transgene.;Overall the findings suggest that ms1 induces a hypertrophic response and provides cardioprotection via a MRTF-SRF signalling mechanism. The findings provide for the first time direct evidence of the involvement of ms1 in hypertrophy and cardioprotection.Mon, 15 Dec 2014 10:34:24 GMThttp://hdl.handle.net/2381/299062014-12-15T10:34:24ZThe role of the CCR5 D32 polymorphism in abdominal aortic aneurysmshttp://hdl.handle.net/2381/29904
Title: The role of the CCR5 D32 polymorphism in abdominal aortic aneurysms
Authors: Sandford, Rebecca M.
Abstract: C-C Chemokine receptor 5 (CCR5) is involved in the regulation of the inflammatory response. Abdominal aortic aneurysms (AAA) may arise as the result of a chronic inflammatory process which is influenced by genetic predisposition. The CCR5 gene is associated with a 32 base pair deletion (the Î”32 polymorphism). The aim of this study was to investigate the role of the CCR5 Î”32 polymorphism in the development of AAA.;A case control study was conducted including 285 patients with AAA and 273 control subjects. A blood sample was taken from each individual and DNA extracted. CCR5 genotype was determined using the polymerase chain reaction (PCR). Flow cytometry was used to investigate the biological activity of the Î”32 polymorphism.;There was no significant difference between the AAA and the control group in relation to the Î”32 allele frequency (AAA group10%, control group=12%, P=0.82, chi squared analysis). Genotype analysis revealed no significant difference between the groups (AAA vs controls, wild type homozygotes=82% vs 77% heterozygotes=16% vs 21%, vs Î”32 homozygotes= 2% and 2% respectively, P=33, chi squared analysis). The polymorphism was shown to be biologically active with the number of Î”32 alleles correlating with cell expression of CCR5 as detected with flow cytometry (P=<0.05).;This study demonstrates that the CCR5 Î”32 is a biologically active genetic polymorphism, however, there is no association between this polymorphism and AAA.Mon, 15 Dec 2014 10:34:23 GMThttp://hdl.handle.net/2381/299042014-12-15T10:34:23ZThe signal averaged P wave : a non-invasive marker of atrial electrophysiological substratehttp://hdl.handle.net/2381/29903
Title: The signal averaged P wave : a non-invasive marker of atrial electrophysiological substrate
Authors: Redfearn, Damian Paul
Abstract: The technological advances made over the last century have afforded the clinician an array of sophisticated tests to aid the diagnostic process. Much of the knowledge gained on the pathophysiology of cardiac disease has been from invasive assessment, often in animals, but also in human subjects. Application of this knowledge to patient care is limited by the need for invasive studies that present some risk of harm to the patient. Non-invasive assessment reduces risk of harm significantly whilst providing information equivalent to invasive assessment. The best example of this is the insight delivered by technological advances in imaging of the heart. Ultrasound echocardiography, radio-isotope imaging, computerised tomography and magnetic resonance imaging have all excelled expectations in delivering accurate anatomic and functional information non-invasively. Assessment of electrophysiologic function began non-invasively with the recording of surface potentials by Augustus D Waller1 and the development of the electrocardiogram (ECG) by William Einthoven2 (who was later awarded the Nobel Prize in 1924 for his endeavours). Recognition of pathology from the surface ECG was hypothesis generating. In order to explore the heart's electrical system further electrophysiological assessment was made invasively to supplement the information obtained from the surface ECG. This information proved favourable and when combined with pacing stimulus protocols provided the clinician with detailed information on conduction properties that could be measured in a reproducible and reliable way to reflect the impact of drugs or disease in detail that the surface ECG could not. Moreover, the invasively measured properties could be linked with changes at the cellular level and thus the effect of changes in ion channel density, for example, on electrophysiologic properties could be predicted. It would obviously be beneficial to somehow gather the information non-invasively, but this has proved more challenging. Firstly, much of the information obtained invasively is the product of pacing protocols that cannot be reproduced non-invasively. Secondly, the detailed assessment of cardiac electrophysiology from surface electrograms is hampered by multiple factors pertaining to the intervening tissue, i.e. body habitus and electrical interference (noise). Given these factors the expectations of non-invasive assessment of cardiac electrophysiology must be limited and cannot be compared to imaging. The utility of non-invasive tests must be in the 'broad stokes' rather than the fine detail. However it is not beyond expectations to provide useful insights that may be employed in the investigation of disease trends and or the impact of intervention. The trade off for lack of detailed information is the safety, low cost and general applicability to a large patient population. The difficulty in gathering further information from the surface ECG has been alluded to briefly above. Digital techniques are used to overcome some of the difficulties such as amplification and noise reduction. Digital applications are then often used to analyse the data gathered. It is useful to be familiar with some of the concepts involved in digital signal processing as it pertains to cardiac signals and thus a brief outline is presented in appendix 1. This thesis begins with a detailed review of the surface P wave in health and disease, and a review of atrial fibrillation (AF) - the most common arrhythmia encountered in clinical practice.Mon, 15 Dec 2014 10:34:23 GMThttp://hdl.handle.net/2381/299032014-12-15T10:34:23ZExtracorporeal membrane oxygenation for severe systemic inflammatory response : development of a rabbit modelhttp://hdl.handle.net/2381/29902
Title: Extracorporeal membrane oxygenation for severe systemic inflammatory response : development of a rabbit model
Authors: Khoshbin, Espeed
Abstract: Hypothesis: ECMO is an acceptable supportive therapy for patients with severe SIRS despite triggering haematic response.;Objectives: To develop a reliable and reproducible animal model of SIRS to investigate strategies for reducing the haematic response.;Materials and Methods: Literature review: (I) The Systemic Thrombo-inflammatory Pathway (STIP). (II) The haematic response. Clinical studies: (I) Institutional review of ECMO for severe SIRS. (II) Comparative review of oxygenators performance. In-vivo studies: Animal experiments, (I) Development of a rabbit model of graded SIRS. (II) Dose response relationship between administered intravenous endotoxin and fatal Multi-organ Dysfunction Syndrome (MODS). (III) Inter-individual variation amongst rabbits receiving a lethal dose of endotoxin. In-vitro studies: Evaluation of the cellular and biochemical components of STIP in rabbits. (I) Development of rabbit ELISA. (II) Determination of the normal range, dose response and inter-individual variation. (III) Immunohistochemical evaluation of endotoxin induced lung injury. (IV) Dose related oxidative stress and DNA damage and (V) apoptosis in rabbit lung.;Results: There is a reciprocal relationship between graded SIRS and the outcome of ECMO. There is a linear relationship between the dose of endotoxin and the development of graded SIRS in rabbits. Significant DNA homology and cross-reactivity exists between humans and rabbits making this a useful model for immune experimentation.;Conclusions: ECMO is superior to conventional ICU management in selected groups of patients. New oxygenator technology has significantly reduced the haematic response to ECMO, however it has failed to influence survival. Cellular components such as neutrophils play a central role in SIRS activation, however thrombin appears to be the common biochemical component for feedback escalation and progression of severe SIRS to MODS.Mon, 15 Dec 2014 10:34:22 GMThttp://hdl.handle.net/2381/299022014-12-15T10:34:22ZRisk stratification of myocardial infarction using cardiac peptideshttp://hdl.handle.net/2381/29901
Title: Risk stratification of myocardial infarction using cardiac peptides
Authors: Khan, Sohail Q.
Abstract: We investigated the TIMI risk score, Cardiotrophin-1 (CT-1) myotrophin and MPO in combination with NTproBNP at predicting adverse outcome following AMI. We recruited 596 patients with AMI. Patients were TIMI risk scored. The concentrations of CT-1, myotrophin, MPO and NTproBNP were measured using non-competitive immunoassays. All patients were followed-up for death, recurrent MI, heart failure (HF) and MACE (death, MI and need for urgent revascularisation). Mortality was related to higher TIMI score (p=0.029) and NTproBNP levels (<0.0001). NTproBNP was an independent predictor of mortality (OR 4.21). The receiver-operating curve (ROC) area under curve (AUC) for NTproBNP was greater than TIMI risk score (0.79 vs. 0.67). CT-1 was raised in death or HF (0.77 vs. 0.73fmol/ml; p=0.001). In multivariate analysis CT-1 (HR 1.5) and NTproBNP (HR2.1) predicted death or HF independently of clinical factors. The ROC AUC for CT-1 was 0.62; NTproBNP was 0.77; AUC for combined markers was 0.84. Myotrophin was raised in patients with death, death or HF and MACE. In Cox analysis myotrophin (HR 5.07) and NTproBNP (HR 7.15) independently predicted death. Myotrophin was better at predicting death or HF (HR 2.35) and MACE (HR 1.69). Median MPO was raised in patients experiencing death, death or MI, death or HF and MACE. In Cox analysis median MPO predicted death (HR 13.05) and death or non-fatal MI (HR 5.07). A multimarker approach with NTproBNP may be useful for risk stratification in AMI patients.Mon, 15 Dec 2014 10:34:21 GMThttp://hdl.handle.net/2381/299012014-12-15T10:34:21ZTelomeres and coronary heart diseasehttp://hdl.handle.net/2381/29899
Title: Telomeres and coronary heart disease
Authors: Brouilette, Scott Wayne
Abstract: Using mean telomere length as a marker of biological age, I show that: 1. Subjects with premature myocardial infarction (MI) have significantly shorter telomeres than age-sex matched, healthy, controls. The mean telomere length in MI subjects was similar to controls almost 11 years older. 2. Healthy young adult children of families with a strong history of premature MI have shorter telomeres than age matched children of families without such a history. 3. Shorter telomere lengths are associated with increase risk of subsequent CHD events in a prospective study. This analysis was carried out on samples collected in the West of Scotland Coronary Prevention Study (WOSCOPS). This randomised blinded trial was designated to examine the benefits of statin treatment on preventing CHD and showed a 30% reduction of events in those treated with pravastatin. Interestingly, my analysis showed that this benefit of statin is only seen in those subjects at higher risk of CHD based on their telomere length.;As the final part of the thesis I carried out a quantitative linkage trait (QTL) analysis in sib-pairs in an attempt to identify genetic loci regulating telomere length. I report the mapping of a major QTL on chromosome 12 that determines almost 50% of the inter-individual variation in mean telomere length.;These findings support a novel "telomere" hypothesis of CHD. They indicate that telomere biology is intimately linked to the genetic aetiology and pathogenesis of CHD. Specifically, the findings suggest that (i) those individuals born with shorter telomeres may be at increased risk of CHD (ii) rather than individual genes, a more global structural property of the genetic material may explain the familial basis of CHD (iii) variation in telomere length may explain, in part, the variable age of onset of CHD. The findings provide several new avenues for future research.Mon, 15 Dec 2014 10:34:21 GMThttp://hdl.handle.net/2381/298992014-12-15T10:34:21ZPlasma matrix metalloproteinasis as predictors of prognosis and left ventricular remodelling after acute myocardial infarctionhttp://hdl.handle.net/2381/29900
Title: Plasma matrix metalloproteinasis as predictors of prognosis and left ventricular remodelling after acute myocardial infarction
Authors: Kelly, Dominic
Abstract: The basis of this thesis was to investigate the role of MMP's and their natural inhibitors' tissue inhibitors of metalloproteinases (TIMP's) in the process of left ventricular remodelling, clinical heart failure and adverse prognosis post acute myocardial infarction (AMI). Methods: We recruited patients post AMI. Stage 1 aimed to examine the temporal profile of several MMP's and their relationship with markers of LV function, volumes and remodelling in a limited population size (n=91). Stage 2 investigated a more extensive population (n=404), concentrating on a limited number of MMP's/TIMP's and included clinical follow up to identify subjects with adverse prognosis. All patients were recruited from the CUU units of the University Hospitals of Leicester. All donated venous blood samples at 0-12hurs, 12-24hrs and at 24hr intervals post symptoms until discharge for measurement of MMP/TIMP's and underwent echocardiographic studies during their index admission and at follow up. During stage 2 all subjects were additionally followed for the clinical endpoints of death or heart failure. Results: We present convincing data to implicate the MMP system in both LV remodelling and adverse prognosis post AMI. Stage I demonstrates individual temporal profiles of MMP's and presents data on determinants of MMP expression. We show an association between MMP-9 and LV dysfunction, volumes and remodelling post AMI. Stage 2 confirms both this data and observes similar results for TIMP-1. In addition we demonstrate the association between both MMP-9 and TIMP-1 with adverse prognosis and compare with N terminal pro BNP as a prognostic marker. A retrospective audit of the effects of diabetes and stress hyperglycaemic is a hypothesis generating chapter which presents association between post MI hyperglycaemia, elevated MMP's and adverse LV function. Summary: Altered MMP/TIMP expression occurs post AMI and is associated with LV dysfunction and remodelling, and with adverse prognosis. The MMP system may represent a potential therapeutic target post AMI.Mon, 15 Dec 2014 10:34:21 GMThttp://hdl.handle.net/2381/299002014-12-15T10:34:21ZInvestigation of renal ischaemia reperfusion injury using an isolated haemoperfused porcine kidney modelhttp://hdl.handle.net/2381/29898
Title: Investigation of renal ischaemia reperfusion injury using an isolated haemoperfused porcine kidney model
Authors: Harper, Simon John Francis
Abstract: The aim of this study was to design and validate an isolated kidney haemoperfusion system while investigating the effects of three key factors influencing early graft injury and function; leucocyte activity, warm ischaemic time (WIT) and perfusion pressure.;Porcine kidneys were perfused with normothermic oxygenated autologous blood on an isolated organ perfusion system (IOPS) designed using cardiopulmonary bypass technology. Physiological and biochemical parameters were measured throughout the 6 hour perfusion period. Interval serum, urine and tissue samples were taken for physiological analysis, histological evaluation and assays measuring oxidative tissue injury, apoptosis and endovascular injury.;Kidneys perfused with leucocyte-depleted blood functioned significantly better than those perfused with whole blood in terms of creatinine clearance, oxygen consumption, acid-base homeostasis and renovascular haemodynamics. Haemoperfused kidneys demonstrated functional deterioration in parallel with increasing periods of warm ischaemia (7, 15, 25 and 40 minutes). Increasing WIT was also associated with elevated serum markers of oxidative protein and lipid injury and these correlated accurately with functional parameters. In contrast, elevated caspase 3 activity was associated with better renal function. A higher perfusion pressure of 95mmHg was associated with significantly improved renal function compared to sub-physiological pressures without increasing endovascular injury.;The IOPS represents a reliable and versatile model of IRI and as such has demonstrated that leucocyte depletion, WIT and perfusion pressure significantly affect early graft injury and function. The system offers extensive scope as a tool for evaluating IRI ameliorating interventions and in clinical organ viability assessment and preservation.Mon, 15 Dec 2014 10:34:20 GMThttp://hdl.handle.net/2381/298982014-12-15T10:34:20ZPre-clinical assessment of the anti-thrombotic and anti-proliferative potential of eptifibatide (IntegrilinTM)-eluting stentshttp://hdl.handle.net/2381/29897
Title: Pre-clinical assessment of the anti-thrombotic and anti-proliferative potential of eptifibatide (IntegrilinTM)-eluting stents
Authors: Chitkara, Kamal
Abstract: No abstract provided.Mon, 15 Dec 2014 10:34:20 GMThttp://hdl.handle.net/2381/298972014-12-15T10:34:20ZFunctional consequences of nociceptin receptor activationhttp://hdl.handle.net/2381/29894
Title: Functional consequences of nociceptin receptor activation
Authors: McDonald, John
Abstract: Nociceptin orphanin FQ (N/OFQ) is the 17 amino acid endogenous ligand for the Gi-coupled N/OFQ-receptor (NOP). In vivo administration produces a wide range of physiological responses including; analgesia, hyperalgesia and anti-opioid actions.;In a series of in vitro assays including [leucyl -3H]N/OFQ binding, GTPgamma[35S] binding and inhibition of cAMP formation the following linked studies were performed; (1)N/OFQ structure-activity relationships (SAR) in cells (CHO) stably expressing human NOP (2)evaluation of receptor density on efficacy using the ecdysone inducible expression system and native tissues, (3)an investigation of NOP/G-protein coupling efficiency.;SAR studies can be summarized as combining arginine14, lysine15 repeat in N/OFQ (increase affinity/potency) with C-terminal [F/G]N/OFQ(1--13)NH2([F/G]) and [Nphe1]N/OFQ(1--13)NH 2([Nphe1]) modifications (reduce/eliminate efficacy). Arg14/Lys15 increased the affinity (pKi:10.31--11.16) and potency (pEC50:8.98--9.85) of N/OFQ. [F/G] and [Nphe 1] reduced the efficacy of N/OFQ from 1.0 to 0.44 and 0. Combination of Arg14/Lys15 and [Nphe1] in UFP-101 produced the highest affinity peptide antagonist available (pA 2:9.13, [Nphe1] alone:7.54). Using the ecdysone inducible expression system it was possible to vary the efficacy of [F/G], between antagonist (alpha:0 upstream/low density), partial agonist (alpha:0.3--0.75) and full agonist (alpha:1). In the mouse vas deferens and colon [F/G] displayed varying degrees of partial agonism possibly indicating differences in NOP receptor density. The binding of GDP and GTP in CHOhNOP was to high and low affinity sites. The fraction of GDP binding to the high affinity site was reduced by N/OFQ (77%, under basal to 32%). The reduction in high affinity binding of GDP appeared dependent on the efficacy of the ligand.;This thesis has identified several new peptides of varying efficacy/potency for use in defining the pathophysiological role(s) of N/OFQ-NOP. Efficacy is not just a property of the ligand but of the assay systems and its input receptor density. A cautious approach to new ligands characterized at a single endpoint is advocated.Mon, 15 Dec 2014 10:34:18 GMThttp://hdl.handle.net/2381/298942014-12-15T10:34:18ZStudies assessing cardiac myocyte renewal and myocardial repair in the adult mammalian myocardiumhttp://hdl.handle.net/2381/29896
Title: Studies assessing cardiac myocyte renewal and myocardial repair in the adult mammalian myocardium
Authors: Shenje, Lincoln Takura
Abstract: The initial aims of this thesis were to investigate whether the myocardium contains resident progenitor cells that contribute to myocardial renewal and whether extra-cardiac bone marrow derived cells contribute to myocardial regeneration. I reveal that the myocardium has the capacity to produce humoral factors that enable extra-cardiac progenitors to survive in vitro though this was insufficient to induce cardiac differentiation. I have shown that the myocardium has the capacity to produce a heterogeneous population of cells in vitro, some of which express cardiac related markers but do not adopt a full cardiac phenotype. When these cells are transplanted into a normal or injured heart they integrate into the myocardium but fail to develop a full mature functional cardiac phenotype. I have set up the frame work for demonstrating and defining the qualitative histological structure of the myocardium using lineage tracing techniques and strengthening the criteria for defining various cell lineages in the heart and therefore demonstrated the deficiencies of seminal studies that claimed that adult stem cells had the capacity to differentiate into cardiomyocytes and secondly that cultured heart explants produce cardiac progenitors. From this work it is clear that more needs to be done to identify the various cell lineages and roles of endogenous cardiac cells. The identification of clusters of perivascular cells expressing cardiac markers using 3 dimensional confocal imaging by two photon molecular excitation provided a different approach for identifying putative cardiac progenitors. This in combination with lineage tracing techniques and cell isolation is now required to identify the role of these interesting perivascular cells in cardiac homeostasis.Mon, 15 Dec 2014 10:34:18 GMThttp://hdl.handle.net/2381/298962014-12-15T10:34:18ZAn investigation into the function and signalling of the endothelial receptor tyrosine kinase Tie 1http://hdl.handle.net/2381/29895
Title: An investigation into the function and signalling of the endothelial receptor tyrosine kinase Tie 1
Authors: Salim, Tasneem Fayez
Abstract: The receptor tyrosine kinase Tie1 is expressed in endothelial cells. The receptor has previously been found to have low kinase activity and poor ability to undergo autophosphorylation. The aim of this study is to define the function and signalling mechanisms used by Tie1.;This study demonstrates that the Tie1 endodomain can undergo tyrosine phosphorylation via its own kinase activity and that this is can be regulated by Tie2. Furthermore, phosphorylation is mainly confined to a carboxy-terminal fragment of the endodomain, containing the kinase domain and thus suggests possible inhibitory sequences may be present in the transmembrane and juxtamembrane regions of the Tie1.;This study also demonstrates that a recombinant Ang1 protein, COMP-Ang1, can stimulate tyrosine phosphorylation of full-length and truncated Tie1 in endothelial cells. Whether this event occurs through Tie1 alone or through Tie2 remains to be answered. This work also shows that following COMP-Ang1 stimulation. Tie1 truncation is not affected. For the first time, it has been shown that COMP-Ang1 stimulation gives rise to a heavily phosphorylated 42kDa protein, thought not to be truncated Tie1 but rather an unknown protein associated with Tie1 in endothelial cells.;Studies to define the function of Tie1 in endothelial cells show that Tie1 protects endothelial cells against apoptosis. Attempts to define whether this effect occurs in non-endothelial cells suggest that the cytoprotective function of Tie1 may be endothelial cell specific.;Work presented in this thesis demonstrates novel findings into the signalling mechanisms and function of Tie1.Mon, 15 Dec 2014 10:34:18 GMThttp://hdl.handle.net/2381/298952014-12-15T10:34:18ZThe effects of non-uniform insonation on ultrasound monitoring of cerebral blood flow changeshttp://hdl.handle.net/2381/29892
Title: The effects of non-uniform insonation on ultrasound monitoring of cerebral blood flow changes
Authors: Sweetman, Lorna
Abstract: Transcranial Doppler is widely used to measure flow velocity in the middle cerebral artery. These measurements are sometimes combined with Doppler power for use as an indicator of cerebral blood flow changes. This is based on the assumption that the power of the Doppler signal depends on the number of scatters within the beam, which is proportional to the vessel area, so any changes in vessel area will be matched exactly by changes in Doppler signal power. A three-dimensional numerical model was developed to incorporate data from beam shape measurements with various vessel shapes and sizes in order to study the appropriateness of this assumption. It was found, using the model, that for a typical, clinical positioning of the ultrasound beam with respect to the vessel the ultrasound field was not uniform and Doppler signal power changes significantly underestimated vessel area changes. A flow phantom was set up to investigate the effects in vitro, and in vivo recordings from a number of volunteers were also studied. Evidence of non-uniform insonation was seen in both situations, indicating that power and area changes are not equivalent. Using the spectra from the in vitro and in vivo recordings, it was possible to estimate the shape of the insonating beam and its size relative to the insonated vessel. However, the variance in the beam estimate prevented a direct measurement of changes in vessel size. Instead, a look-up table was derived to allow a correction of signal power measurements to account for non-uniform insonation effects.Mon, 15 Dec 2014 10:34:17 GMThttp://hdl.handle.net/2381/298922014-12-15T10:34:17ZHaematological and clinical factors influencing thrombus formation, structure and fibrinolysishttp://hdl.handle.net/2381/29893
Title: Haematological and clinical factors influencing thrombus formation, structure and fibrinolysis
Authors: Jones, Chris I.
Abstract: This work investigates how changes in the thrombus over time, and in the action of platelets, brought about by physiological or therapeutic factors, influence the susceptibility of thrombi to fibrinolysis. Resistance to fibrinolysis increased with thrombus age, and was associated with expression and/or release of FXIII, TAFI, PAI-1, and FXI, by cells within the thrombus, the recruitment of which was largely platelet dependant. Platelets increase resistance to fibrinolysis through release of FXIII and TAFI, and act pro-fibrinolytically through the recruitment of monocytes, and, by a yet undetermined mechanism, when hyper-activated. Overall, the action of platelets is anti-fibrinolytic, as evidenced by the increase in fibrinolysis associated with reduced platelet number or activity. The plasma expander dextran had no discemable direct effect on platelets, although it did significantly increase the generation of plasmin and the rate of fibrinolysis. This, indirectly, led to a reduction in vWF activity and platelet response to thrombin, but not to TRAP, collagen, or ADP, indicating the these effects result non-specific proteolytic cleavage by plasmin. The contrast media lodixanol or lohexol increased both thrombus formation and resistance to fibrinolysis, whilst Ioxaglate inhibited thrombus formation. These change may in part be due to increased degranulation but is more likely to result from their effect on fibrin fibre formation. These data have implications for clinical resolution of occlusive arterial thrombotic events. Thrombolytic therapy may be more successful if targeted to individuals with lower platelet counts or on long term anti-platelet therapy, and if administered rapidly after thrombus formation. Furthermore low dose Dextran therapy maybe a useful adjuvant to pre-hospital thrombolytic therapy.Mon, 15 Dec 2014 10:34:17 GMThttp://hdl.handle.net/2381/298932014-12-15T10:34:17ZAn investigation into the cytokine expression profile of the abdominal aortic aneurysm wallhttp://hdl.handle.net/2381/29890
Title: An investigation into the cytokine expression profile of the abdominal aortic aneurysm wall
Authors: Middleton, Rachel Katharine
Abstract: Abdominal aortic aneurysm is a disease commonly found in elderly males involving dilatation of the abdominal aorta. The aneurysm wall is characterised by a decrease in the elastin/collagen ratio, apoptosis of smooth muscle cells and a prominent inflammatory infiltrate. Degradation of the extracellular matrix has been attributed to matrix metalloproteinases (MMP), the expression and activation of which is tightly regulated by inflammatory mediators such as cytokines. The presence of an inflammatory infiltrate is a potential source of cytokines within the aneurysm wall.;The aim of this thesis is to investigate the nature of the cytokines that are expressed within the aneurysm. Further work aims to characterise the expression of key cytokines and to investigate their effect on MMP expression.;The cytokine profile of the aneurysm wall was measured using a 42-cytokine protein array. Overall, a number of pro-inflammatory cytokines, chemokines and growth factors were raised within the aneurysm wall. Interleukin-6 (IL-), IL-8, monocyte chemoattractant protein-1 (MCP-) and MCP-2 were highly elevated in the aneurysm above the physiological levels found in abdominal and thoracic aorta.;The expression of chemokines within the aneurysm wall was characterised further using immunohistochemistry. IL-8 was found to co-localise with the infiltrate, which was predominantly formed from CD20+ B-lymphocytes and CD3+ T-lymphocytes, whilst MCP-1 co-localised to CD68+ macrophages.;The effect of IL-8 on the expression of MMP-2 and MMP-9 was investigated through an in vitro aneurysm model. The results showed that MMP-2 was expressed constitutively, whilst MMP-9 expression from the same culture decreased with time. IL-8 did not effect MMP-2 and MMP-9 expression.;In conclusion, the abdominal aortic aneurysm wall is a highly pro-inflammatory and chemotactic environment. Co-localisation of IL-8 and MCP-1 with the infiltrating cells suggests a role for these cytokines in aneurysm pathogenesis. However, a direct involvement between IL-8 and MMP expression is unlikely.Mon, 15 Dec 2014 10:34:16 GMThttp://hdl.handle.net/2381/298902014-12-15T10:34:16ZInvestigating short-term blood pressure regulation : peripheral baroreceptor sensitivityhttp://hdl.handle.net/2381/29891
Title: Investigating short-term blood pressure regulation : peripheral baroreceptor sensitivity
Authors: Peirce, Susan Caroline
Abstract: Autonomically-mediated baroreflex control of heart rate has been extensively studied (cardiac BRS, cBRS), but peripheral control of blood pressure is less well known. Total peripheral resistance (TPR) was derived from pulse contour stroke volume (SVPC) using non-invasive blood pressure (Finapres). The beat-to-beat variability of Finapres SVPC was evaluated in cardiac catheterisation patients against aortic blood pressure SVPC. Correlations were generally good (mean R = 0.75), but regression slopes tended to be less than unity and several aortic recordings were significantly affected by the dynamic response of the measurement system. Finapres SVPC was also compared to Doppler stroke distance (SD) in healthy volunteers. Both measures followed respiratory movements well, although SVPC had higher coherence with respiration. Discrepancies between the results were considered to be mainly due to errors in the Doppler method. Coherence thresholds for spectral cBRS were determined as a function of the number of subrecords available for ensemble averaging and the effect of ventricular ectopics on cBRS estimates was investigated. Pulse contour TPR data was then used to determine peripheral BRS (pBRS) in healthy controls and neurocardiogenic syncope patients (NCS) using methods adapted from cardiac BRS analysis. Diastolic pressure produced greater pBRS estimates than systolic pressure and pBRS was generally higher in patients and fainters than in controls and non-fainters. Tilt did not have a consistent effect on pBRS and it was not linearly related to age or resting blood pressure, although it may be increased in hypertension and the elderly. pBRS was able to discriminate between the subject groups when cBRS methods showed no difference.Mon, 15 Dec 2014 10:34:16 GMThttp://hdl.handle.net/2381/298912014-12-15T10:34:16ZProcessing of radio-frequency ultrasound signals from blood and cerebral embolihttp://hdl.handle.net/2381/29889
Title: Processing of radio-frequency ultrasound signals from blood and cerebral emboli
Authors: Cowe, Joanne
Abstract: Transcranial Doppler ultrasound (TCD) is commonly used to detect emboli in the cerebral circulation. However, current techniques to discriminate between signals from emboli and artefacts are subjective and ambiguous. The radio-frequency (RF) signal provides an extra dimension to the information available from conventional TCD systems, which may help to interpret complex events. Artefacts generated by healthy volunteers and embolic signals recorded from a flow phantom were used to characterize the appearance of the two types of event. Characteristics of events, recorded during and immediately after carotid endarterectomy surgery, were compared to those from known sources. Additional information was provided by the RF signal, on events recorded during TCD monitoring, thus aiding classification. The RF signal may have a role as a gold standard for embolus detection. Embolic signals appear as uniform and predictable shapes within the RF signal, enabling pattern recognition and image processing techniques to be used for their automated detection. Principal component analysis (PCA) has been used to characterize the typical variation in embolic signal shape, within the RF signal, using training sets of in vitro and in vivo data. PCA techniques were also utilised to discriminate between previously unseen embolic and artefact signals. The algorithms developed did not have the accuracy required for their use in a clinical setting but do have the potential to be developed further. Mathematical modelling and in vitro experiments were carried out to assess the feasibility of using coded-excitation and pulse-compression within a TCD system to improve the bandwidth and hence the axial resolution.Mon, 15 Dec 2014 10:34:15 GMThttp://hdl.handle.net/2381/298892014-12-15T10:34:15ZSustained ventricular arrhythmias : population based study of presentation, management and mortalityhttp://hdl.handle.net/2381/29888
Title: Sustained ventricular arrhythmias : population based study of presentation, management and mortality
Authors: Pathmanathan, Ravi Kumar.
Abstract: BACKGROUND: Sudden cardiac death (SCD) due ventricular tachycardia (VT) or fibrillation (VF) is a major cause of death in the developed world. It is associated with a high recurrence rate and poor prognosis. There has been very little published about VT/VF in a population setting. In this thesis, the incidence of VT/VF, patient demographics, management and survival in a population setting are examined. METHODS: During the two year period between 1 February 1997 and 31 January 1999, all patients presenting with a sustained episode of VT/VF, unrelated to an AMI, to all 32 coronary care units in the Midlands region of England (population 9.1 million) were entered into a registry. Demographics, clinical history, management as well as mortality data were collected. RESULTS: Six hundred and eight-nine patients presenting with VT/VF were registered giving a minimum annual incidence rate of 38 per million population. Two hundred and nine (30%) of patients underwent electrophysiology (EP)-guided therapy with 89 ICDs implanted. Fifty patients underwent coronary artery bypass grafting (CABG) during the index admission. There were 210 (30%) deaths in total of which 10 were following CABG. EP-guided treatment did not confer a survival benefit but ICD treatment did despite relatively small numbers of ICDs implanted. The benefit of ICD therapy was most impressive in patients with poorer LVEF. Age, VT/VF needing defibrillation, reduced LVEF and diabetes are poor prognostic markers. VT/VF patients undergoing CABG had double the predicted Parsonnet and four times the predicted EuroSCORE mortality rates, suggesting that preceding VT/VF is an important additional risk factor. Relative risk calculations of meta-analysis of ICD trials applied to the registry suggest between 7 to 12 ICDs will need to be implanted per annum to save one life. The registry also demonstrated that 79% of deaths of these SCD survivors occurred in-hospital and less than 15% of these deaths were classed as being arrhythmic.Mon, 15 Dec 2014 10:34:15 GMThttp://hdl.handle.net/2381/298882014-12-15T10:34:15ZThe mechanism of cell death in the human diabetic myocardiumhttp://hdl.handle.net/2381/29887
Title: The mechanism of cell death in the human diabetic myocardium
Authors: Chowdry, T. Mohammed Fiyaz
Abstract: The importance of apoptosis in ischaemia-reoxygenation of the diabetic human heart is unclear. Right atrial appendages were obtained from non-diabetics, non-insulin dependent diabetics (NIDDM) and insulin dependent diabetics (IDDM) at the time of cardiac surgery. Free-hand tissue secretions were subjected to the following protocols: fresh tissue, aerobic control for 210 min, 90 min simulated ischaemia followed by 120 min reoxygenation (SI/R). Cell death by apoptosis and necrosis in non-ischaemic fresh tissue was greater in the NIDDM and the IDDM groups than in the non-diabetic group (p<0.05 in all instances). After SI/R, apoptosis and necrosis were also significantly greater in NIDDM and IDDM groups than in non-diabetics (p<0.05). The mean values of activation of Effector caspase were greater in fresh tissue in the NIDDM and IDDM groups than in the non-diabetic group (p<0.05) and values were further increased after SI/R in the NIDDM and IDDM groups as compared with non-diabetic group (p<0.05). Importantly caspase-3 inhibition reduced apoptosis by 94.0+/-1.6% in the myocardium from non-diabetics and 50.6+/-4.2% in the muscles from diabetics (p<0.05) without influencing necrosis. However, caspase -2 inhibition had no effect on either apoptosis or necrosis. Poly (ADP-ribose) Polymerase (PARP) inhibition resulted in a similar reduction in apoptosis (85.3+/-0.9% and 87.1+/-2.1%) and in necrosis (39.8+/-5.0% and 30.0+/-3.3%) in the muscles from non-diabetic and diabetics. The human diabetic myocardium is also more susceptible to ischaemia/reoxygenation injury than the non-diabetic myocardium, an effect that is mediated, at least in part, by caspase and PARP activation.Mon, 15 Dec 2014 10:34:14 GMThttp://hdl.handle.net/2381/298872014-12-15T10:34:14ZPharmacological characterisation of recombinant vanilloid receptorshttp://hdl.handle.net/2381/29885
Title: Pharmacological characterisation of recombinant vanilloid receptors
Authors: Lam, Patricia May Wah
Abstract: In HEK cells expressing human and rat isoforms of TRPV1, capsaicin, anandamide (an endocannabinoid), olvanil (a structural analogue of capsaicin) and ethanol displayed TRPV1 activity. in contrast, Delta9-THC (an exocannabinoid) did not. No significant difference occurred between human and rat with respect to capsaicin and anandamide activity at 22ÂºC or 37ÂºC. Anandamide displayed partial agonism relative to capsaicin at both temperatures at rat only. Anandamide was also an agonist at cannabinoid CB1 receptors. Capsazepine, a competitive TRPV1 antagonist, inhibited capsaicin, olvanil and anandamide response; was not temperature-dependent but displayed a 6-fold higher potency at human TRPV1.;The first neuronal model to express recombinant human TRPV1 was produced by sub-cloning and transfection into the neuroblastoma SH-SY5Y cell-line, a more physiologically relevant system. Pharmacological characterisation confirmed expression of TRPV1 with comparable pharmacology to non-neuronal models in this thesis. For example, capsaicin pEC50/capsazepine pKB in HEk (human TRPV1) and SH-SY5Y were 6.77/6.75 and 6.63/7.44 respectively. In SH-SY5Y cells, the agonist resiniferatoxin displayed the highest potency (pEC50 9.03). Iodo-RTX, an antagonist, revealed a higher affinity than capsazepine. Capsaicin-mediated increases in intracellular calcium (pEC50 6.63) in SH-SY5Y cells were sufficient to sustain [3H]noradrenaline release (pEC50 9.21). In a perfusion system, it was shown that the two events were temporally linked.;Overall, these findings have: 1. expanded current knowledge of TRPV1 pharmacology. 2. established a neuronal model for further studies, especially TRPV1 desensitisation.Mon, 15 Dec 2014 10:34:13 GMThttp://hdl.handle.net/2381/298852014-12-15T10:34:13ZRole of platelets in the procoagulant environment in bloodhttp://hdl.handle.net/2381/29886
Title: Role of platelets in the procoagulant environment in blood
Authors: Appleby, Jackie A.
Abstract: The project investigated the mechanisms whereby platelets expose a procoagulant surface and induce tissue factor (TF) in monocytes. A whole blood flow cytometric assay to measure phosphatidylserine (PS) exposure on platelets was established and validated. Using this assay, it was demonstrated that collagen is the primary agonist in eliciting platelet PS exposure, individuals' platelets vary in their response to collagen, and not all express PS despite maximal activation. Collagen-induced PS exposure was independent of other aspects of platelet activation. ADP enhanced the procoagulant effect of collagen, but could not induce PS exposure on its own. The potentiating effect of ADP was mediated mainly through P2Y12 and was required for the formation of microparticles. Procoagulant microparticles were enriched in CD42b and P-selectin, but had reduced ability to bind fibrinogen. Thrombin could instigate PS exposure only where there was platelet-platelet contact. These data suggest that at a wound site, platelet PS exposure is stimulated by subendothelial collagen at the same time as coagulation is initiated by TF. It is not dependent on initial thrombin generation but thrombin and ADP perpetuate thrombin generation by promoting PS exposure where there is platelet-platelet contact within a thrombus. Activated platelets caused upregulation of gene expression of monocyte TF within 2 hours, and, at a later stage, of its inhibitor, tissue factor pathway inhibitor. These effects were primarily mediated via soluble factors. Analysis of TF antigen on monocytes and monocyte-platelet aggregates by flow cytometry suggested that TF might be platelet-associated.Mon, 15 Dec 2014 10:34:13 GMThttp://hdl.handle.net/2381/298862014-12-15T10:34:13ZPharmacological characterisation of recombinant nociceptin receptorshttp://hdl.handle.net/2381/29884
Title: Pharmacological characterisation of recombinant nociceptin receptors
Authors: Barnes, Timothy Andrew
Abstract: The heptadecapeptide Nociceptin/OrphaninFQ (N/OFQ) is the endogenous ligand for the G-protein coupled receptor, NOP, activation of which is involved in a plethora of physiological functions, including pain. Studies in main are hampered by a relative lack of suitable, well characterised ligands, especially antagonists and an understanding of the effects of prolonged receptor activation.;The N/OFQ sequence can be divided into a message domain, associated with receptor activation and an address domain, associated with receptor binding. In a series of biochemical assays, using Chinese Hamster Ovary (CHO) cells stably expressing human NOP, a number of ligands suitable for in vivo animal testing were characterised including a high affinity, high potency agonist ([(iF)Phe4, Arg14, Lys15]N/OFQ-NH2), a high affinity antagonist ([Nphe 1, Arg114, Lys15]N/OFQ-NH 2 or UFP-101) and several partial agonist molecules.;In a CHO cell line expressing NOP at a range of levels via the ecdysone inducible expression system, and behaviour of the partial agonist [F/G]N/OFQ(1-13)-NH 2 could be modulated to encompass full agonism and antagonism, using the previous assays, underscoring the need to assess activity in a range of models and steps in the signal transduction cascade.;Receptor desensitisation, by prolonged exposure of the inducible cells to N/OFQ, led to a decrease in NOP density, a reduction in N/OFQ stimulated GTPgamma[35S] binding with a reduction in functional potency and a reduction in potency of cAMP inhibition. More interestingly, a reduction in NOP mRNA was also observed.;Collectively this thesis has made a significant contribution to the N/OGQ-NOP field in that: (1) several novel molecules have been characterised and are now available to other researchers; (2) a system in which pharmacological behaviour can be accurately defined has been characterised; (3) the first example of genomic desensitisation of NOP has been described. The N/OFQ-NOP system is ready to leave the pre-clinical laboratory and full clinical evaluation is eagerly awaited.Mon, 15 Dec 2014 10:34:11 GMThttp://hdl.handle.net/2381/298842014-12-15T10:34:11ZNew insight into the signalling pathways of cardioprotection in the non-diabetic and diabetic human myocardiumhttp://hdl.handle.net/2381/29882
Title: New insight into the signalling pathways of cardioprotection in the non-diabetic and diabetic human myocardium
Authors: Hassouna, Ashraf.
Abstract: Background: The cardioprotection by IPC is a well-recognised phenomenon in healthy hearts, however the occurrence of IPC in diabetics is controversial. In this thesis I have investigated whether the diabetic myocardium can be preconditioned and the underlying mechanisms. Methods and results: Right atrial sections from 3 groups of patients: non-diabetics, IDDM, and NIDDM were randomised to receive one of the following protocols: aerobic perfusion, simulated ischaemia/reoxygenation, IPC, and pharmacological preconditioning with phenylephrine, adenosine, diazoxide (mitoKATP channel opener), PMA (protein kinase C agonist) or anisomycin (p38 MAPK activator). The assessment of CK leakage and MTT tissue viability at the end of the experiments demonstrated that diabetic myocardium cannot preconditioned by ischaemia or by the pharmacological activation of the signal transduction pathway upstream of mitoKATP channels but that protection can be obtained by the activation of the pathway beyond mitoKATP channels (e.g. PKC and P38 MAPK). In a second study, mitochondria isolated from the above groups of patients were used to assess for MMP after treatment with diazoxide by measuring the uptake of JC-1 dye. The partial depolarisation of MMP seen in non-diabetics was absent in the diabetic myocardium. The determination of ROS generation by the mitochondria of the non-diabetic and diabetic myocardium exposed to diazoxide showed an altered response in superoxide production in the diabetic myocardium. Finally, using specific PKC isoform inhibitors, I demonstrated that PKC a and PKC e are the two isoforms involved in IPC of human myocardium with PKCe begin upstream and PKCa being downstream of mitKATP channels. Conclusions: The failure to precondition the diabetic myocardium is caused by mitochondrial dysfunction. Since PKCa is the isoform beyond mitoKATP channels, this and P38 MAPK may represent potential clinical and therapeutic targets to protect the diabetic myocardium.Mon, 15 Dec 2014 10:34:10 GMThttp://hdl.handle.net/2381/298822014-12-15T10:34:10ZCharacterization of interaction sites between Kir6.0 and SUR subunits of ATP-sensitive potassium (Katp) channelshttp://hdl.handle.net/2381/29883
Title: Characterization of interaction sites between Kir6.0 and SUR subunits of ATP-sensitive potassium (Katp) channels
Authors: Aljohi, Mohammed
Abstract: This study investigated cytoplasmic inter-subunit interactions between the Kir6.2 and SUR2A subunits of the cardiac ATP-sensitive potassium channel. The channels are a heterooligomeric complex of pore-forming Kir6.2 subunits and sulphonylurea receptor (SUR2A) subunits. Interactions between the cytoplasmic loops, the nucleotide binding domains (NBF1 and NBF2) of SUR2A and the full length of Kir6.2 were determined. In co-immunoprecipitation experiments, fragments from the C-terminal of SUR2A containing residues 1294-1358 tagged with Maltose-binding protein (MBP) showed binding with the full length Kir6.2 subunit, while residues between 1358-1545 did not. This indicated involvement of a 65 amino acid domain in the proximal C-terminal of SUR2A in forming a direct interaction with Kir6.2. When HEK 293 cells stably expressing Kir6.2/SUR2A channels were transiently transfected with SUR2A fragments containing residues 1294-1359, KATP current was decreased. This current reduction was due to a decreased number of channel subunits in the cell membrane; this was demonstrated by using immunocytochemistry, which showed that anti-K ATP channel subunit-associated fluorescence was lower in the cell membrane and increased in the intracellular compartment in the presence of the binding region.;Use of SUR2A/MRP1 chimaeras of the putative binding domain showed that the last eleven amino acids of the binding region were important for binding activity but that they do not contain all the elements necessary for binding. Co-immunoprecipitation and assays of disruption of functional channels with the binding domain chimaeras suggested an important role for the residues between 1318 and 1337 in the Kir6.2 binding motif within the SUR2A C-terminal domain.Mon, 15 Dec 2014 10:34:10 GMThttp://hdl.handle.net/2381/298832014-12-15T10:34:10ZIn vitro and ex vivo studies of the effects of immunosuppressive agents on human plateletshttp://hdl.handle.net/2381/29879
Title: In vitro and ex vivo studies of the effects of immunosuppressive agents on human platelets
Authors: Hayes, Natalie Jayne.
Abstract: This work investigates the effects of immunosuppressants on platelet activity in renal allograft recipients and end-stage renal failure patients.;Methods: Blood from patients with end-stage renal failure (n=21) was incubated with physiological doses of cyclosporine, tacrolimus, and rapamycin. Non-stimulated and stimulated platelets were analysed for P-selectin expression and fibrinogen binding as measures of platelet activity.;Ex vivo platelet activity was assessed in transplant recipients taking rapamycin, cyclosporine, tacrolimus, or azathioprine (n=18 for each).;Results: 1. Platelet-bound fibrinogen was increased by incubation with cyclosporine, tacrolimus, and rapamycin. This effect was exaggerated in stimulated platelets; 2. Cyclosporine, tacrolimus, and rapamycin increased P-selectin expression in resting platelets. Positive dose effects were exhibited by the calcineurin inhibitors. Decreased P-selectin expression was observed with calcineurin inhibitor and rapamycin exposure in stimulated patients; 3. Resting and stimulated platelets from patients taking cyclosporine, tacrolimus and rapamycin bound less fibrinogen and expressed less P-selectin than controls; 4. Platelets exposed to rapamycin in vitro exhibited clumping. This was not seen ex vivo and platelet activation was lower in patients taking rapamycin compared to controls; 5. Larger spleen size was observed with rapamycin, cyclosporine, and tacrolimus use compared to the azathioprine group. All three drugs were associated and increased platelet size.;Conclusions: This study demonstrates that these immunosuppressants stimulate human platelets in vitro. This may occur through increased P-selectin expression and fibrinogen binding. It also suggests these agents disrupt platelet function in vivo, although the nature of this interaction is less clear. Altered platelet morphology and increased spleen size with rapamycin use may be implicated in rapamycin-induced thrombocytopenia. These results support a role for platelets in renal transplantation and identify several avenues for further study, particularly concerning the role of anti-platelet therapy in the transplant population.Mon, 15 Dec 2014 10:34:09 GMThttp://hdl.handle.net/2381/298792014-12-15T10:34:09ZPlatelet reactivity, polymorphisms and premature myocardial infarctionhttp://hdl.handle.net/2381/29880
Title: Platelet reactivity, polymorphisms and premature myocardial infarction
Authors: Singh, Ravi Kumar
Abstract: I have carried out a detailed assessment of platelet function and reactivity in 205 subjects that suffered a premature MI (at a mean age 42.3 +/- 5.7) and 200 age and sex matched controls, to two endogenous platelet agonists adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP). I have further analysed the effect on platelet function of polymorphisms in two platelet receptors (GPIIbIIIa C196T and GPIaIIa G873A), which have been proposed as genetic risk factors for MI.;Platelet reactivity to several concentrations of ADP and TRAP, measured as degree of fibrinogen binding by flow cytometry, showed marked inter-individual variation (4-5 fold) in both cases and controls. There was a strong correlation between the ADP and TRAP responses and experimental analysis suggested that this was because the TRAP response is substantially mediated via the ADP receptor.;Expression of the GPIaIIa receptor on the platelet surface showed up to 10-fold variation between subjects. The G837A polymorphism in the GP1a gene had a marked effect on GPIaIIa expression (accounting for about one-fifth of the variation) but did not influence the risk of MI (odd ratio 1.12 (95%CI 0.86-1.46)).;Expression of the GPIIbIIIa receptor in both the resting state and after agonist stimulation was not affected by C196T polymorphism in the GPIIIa gene and did not influence risk of MI (odds ratio=0.94 (0.61-1.45)).;Of the emerging risk factors, fibrinogen (p<0.001) and Lp(a) (p = 0.016) were higher in the cases. There were significant effect of the G455A polymorphism in the fibrinogen beta chain gene and the C93T polymorphism in the apolipoprotein (a) gene on fibrinogen and Lp(a) levels, respectively.Mon, 15 Dec 2014 10:34:09 GMThttp://hdl.handle.net/2381/298802014-12-15T10:34:09ZApoptosis and necrosis in ischaemia/reoxygenation injury of the human myocardium : mechanism of protection by ischaemic preconditionnghttp://hdl.handle.net/2381/29881
Title: Apoptosis and necrosis in ischaemia/reoxygenation injury of the human myocardium : mechanism of protection by ischaemic preconditionng
Authors: Vohra, Hunaid Ahmed
Abstract: Gene ChipRTM microarrays were used to analyse mRNA isolated from right atrial appendages (n=3/group) subjected to SI/R, IPC and caspase-3 inhibition. The initial studies were carried out with specific ischaemia/reoxygenation time-points. Apoptosis was shown to be greater than necrosis after 90min simulated ischaemia (SI) and 8h reoxygenation (R) but necrosis was greater than apoptosis by 24hr R. Inhibition of caspase-8+9 by z.IETD.fmk+z.LEHD.fmk (70nM) significantly reduced apoptosis following 90min SI and 2hr R and inhibition of caspase-3 by z.DEVD.fmk (70nM) almost completely abolished apoptosis, both without effecting necrosis. I have also shown that ischaemic preconditioning (IPC) is more efficacious in reducing apoptosis than necrosis. IPC inhibits necrosis in the human myocardium by signal transduction pathways that involve mitoKATP channels, PKC and p38MAPK. However, apoptosis that is inhibited by activation of mitoKATP channels and PKC is p38MAPK-independent. The observed changes in gene expression may help to understand the pathophysiology of ischaemic/reoxygenation injury and the mechanism of cardioprotection. With the information obtained in this thesis we have gained more information on the role of apoptosis in ischaemia/reperfusion injury of the human myocardium and a greater understanding of the underlying mechanisms and the signal transduction of cardioprotection by IPC. It is hoped that this knowledge will contribute to the design of therapeutical strategies that may reduce myocardial ischaeia/reperfusion injury in man..Mon, 15 Dec 2014 10:34:09 GMThttp://hdl.handle.net/2381/298812014-12-15T10:34:09ZRisk stratification for revascularisation in acute ischaemic syndromeshttp://hdl.handle.net/2381/29878
Title: Risk stratification for revascularisation in acute ischaemic syndromes
Authors: Constantinides, Savvas Sophocles
Abstract: Aim of study: PHASE 1: To identify those clinical and simple anatomical variables that could predict early (30 days), medium (6 month) and late (1 year) mortality following Percutaneous Coronary Intervention (PCI) for non ST segment elevation Acute Coronary Syndromes (NSTEACS). To compare outcomes in a contemporary group undergoing Coronary artery Bypass Surgery (CABG) and to examine which clinical variables are related to early mortality. PHASE II: To develop a PCI risk score and apply it to the same database. To then apply the risk score to a separate cohort of patients for validation.;Methods: Data from 630 consecutive patients undergoing PCI for NSTEACS between January 1999 and December 2000 were analysed. Data from 522 patients who underwent CABG were also analysed for similar variables and outcomes were noted. The derived 8 variable PCI risk score was applied on the following 500 consecutive patients undergoing PCI for NSTEACS between January 2001 and August 2002.;Results: Age, partial revascularisation, peripheral vascular disease, diabetes mellitus and left ventricular impairment were found to be significant predictors of mortality following PCI for ACS. A 'risk-score' model including age, LV impairment, multi-vessel disease, diabetes, renal impairment, peripheral vascular disease and female sex was then tested on the same cohort and found to be good in predicting death following PCI. In the surgical study group higher rates of mortality were found with age, clinical features of heart failure, LV impairment, chronic airways disease and cerebrovascular disease. The derived PCI risk score was found on validation to be a good predictive tool for mortality.;Conclusion: Individualisation of risk stratification for patients undergoing revascularisation for acute coronary syndromes is not only possible but also simple using easily available clinical information by the bedside.Mon, 15 Dec 2014 10:34:08 GMThttp://hdl.handle.net/2381/298782014-12-15T10:34:08ZChanges to endothelial cell function induced by hydrogen peroxide : a model of cell senescencehttp://hdl.handle.net/2381/29877
Title: Changes to endothelial cell function induced by hydrogen peroxide : a model of cell senescence
Authors: Tull, Samantha Petula.
Abstract: Endothelial dysfunction is an early stage in atherosclerosis and is associated with oxidative stress, which occurs when reactive oxygen species are not fully compensated by cellular antioxidants. This study investigated the effects of hydrogen peroxide in a human endothelial cell model. EA.hy926 cells incubated for 1 hour at 37Â°C with increasing concentrations of hydrogen peroxide were investigated for DNA damage ('Comet' assay), changes in mitochondrial activity (MTT assay), apoptosis and necrosis (Annexin V assay), cell growth and senescence (changes in morphology, cell size, pH6 specific B-galactosidase (S-Gal) and telomere shortening). Changes in the expression of mRNA transcripts of thrombotic (tissue factor); fibrinolytic (tissue phasminogen activator and plasminogen activator inhibitor-1) and adhesion (ICAM-1) proteins were investigated using RT-PCR. Low (&le;50muM) concentrations of hydrogen peroxide induced detectable, but reversible, DNA damage; which was accompanied only by a small decrease in mitochondrial activity. Intermediate levels of oxidative stress (<200muM H2O2) resulted in a dose-dependent effect on DNA damage and mitochondrial function. Exposure to hydrogen peroxide concentrations equal to or above 200muM caused immediate changes in a sub-set of the cells, including apoptosis (n=4). In the surviving cells proliferative ability was reduced, and senescent-like cells developed; indicated by an increase in S-Gal positive cells, a skewed increase in cell size and the appearance of 'giant' cells, but not by changes in telomere length. Tissue Factor and ICAM-1 mRNA levels increased with a corresponding increase in surface ICAM-1 protein expression, but there was no effect on either of the fibrinolytic factor transcripts (n=3). This study demonstrated that endothelial cells surviving an oxidative insult showed an altered phenotype becoming more adhesive and possibly more thrombogenic in parallel with the appearance of senescence. In vivo, these changes would accelerate the progression of atherosclerothrombosis and lead to an impaired ability to repair further injury to the endothelium.Mon, 15 Dec 2014 10:34:07 GMThttp://hdl.handle.net/2381/298772014-12-15T10:34:07ZThe differential expression of microrna in abdominal aortic aneurysmshttp://hdl.handle.net/2381/29257
Title: The differential expression of microrna in abdominal aortic aneurysms
Authors: Stather, Philip William
Abstract: Abdominal aortic aneurysms (AAA) account for 5,251 deaths per year in the UK (2010). Their current incidence in the NHS AAA screening programme is 1.8%, however the vast majority are small. These patients therefore undergo surveillance prior to the need for surgical intervention.
Biomarkers for AAA have been extensively studied, with a meta-analysis, conducted herein, identifying a significant association between several biomarkers and AAA (upregulation of matrix metalloproteinase-2, matrix metalloproteinase-9, tissue inhibitor of matrix metalloproteinase-1, interleukin-6, interleukin-10, tumour necrosis factor-α, osteoprotegerin, osteopontin, interferon-γ, intercellular adhesion molecule-1, vascular cell adhesion protein-1, D-dimer, C-reactive protein, alpha-1 antitrypsin, fibrinogen, triglycerides, and lipoprotein(a), and downregulation of apolipoprotein-A and high density lipoprotein). However, the sensitivity and specificity of these biomarkers is poor, therefore this thesis aimed to look at the expression of microRNAs (miRNAs) in AAA, hitherto previously unstudied.
MiRNAs are short, non-coding RNA sequences which are transcribed from DNA, however they are not translated into protein. They exert their effect by attaching to messenger RNA (mRNA) and causing repression of translation into protein, and deadenylation, thus causing mRNA degradation. MiRNAs are capable of interacting with over 60% of known genes.
The studies within this thesis have undertaken a case control discovery and validation study into miRNAs in AAA, identifying a significant upregulation of 29 miRNAs within the discovery study, 4 of which were validated in blood (let-7e, miR-15a, miR-196b, miR-411), and miR-196b being further validated in plasma. There was however no miRNA dysregulation found in aortic tissue. In addition, these 4 miRNAs were found to have significant interactions with previously studied AAA biomarkers identified through earlier systematic review and meta-analysis.
The 4 miRNAs identified within this thesis were similarly dysregulated in patients with peripheral arterial disease, therefore they may be dysregulated due to generalised atherosclerosis rather than AAA, and must be interpreted with caution.Thu, 06 Nov 2014 11:54:01 GMThttp://hdl.handle.net/2381/292572014-11-06T11:54:01ZDevelopment of novel therapeutic approaches for the reduction of apolipoprotein B expressionhttp://hdl.handle.net/2381/29049
Title: Development of novel therapeutic approaches for the reduction of apolipoprotein B expression
Authors: McLaughlin, Catherine Louise
Abstract: Atherosclerosis is a chronic inflammatory disease of the arteries that represents the root cause of the majority of myocardial infarctions and strokes. The entry and accumulation of lipid particles, namely low density lipoprotein (LDL) particles, in the intima of the artery wall is a key step in the development of atherosclerotic lesions. Apolipoprotein B100 is the principal protein covering LDL particles and is necessary for their production by the liver. Currently, the most widely prescribed lipid lowering drugs are statins, which achieve only up to ~30% reduction of circulating LDL and are not suitable for all patients due to undesirable side effects; therefore novel means of LDL reduction are desirable. Pyrrole-imidazole polyamides are minor groove DNA binders with the potential to inhibit gene expression by binding in place of transcription factors in genetic promoter regions. In this project, small hairpin and a novel form of long linear polyamides, were synthesised to bind to the APOB proximal promoter and their effect on HepG2 hepatocyte expression of APOB and toxicity was investigated. Although polyamides successfully entered the cell nucleus, they did not inhibit APOB transcription. A library of natural product extracts was then screened to identify extracts which inhibited APOB promoter activity. Four extracts with such activity were identified and one with low toxicity was fractionated using liquid chromatography in an attempt to purify key active molecules that could be used as the basis for a novel therapeutic. Taken together, the results of this study have identified some limitations of polyamide technology, but also a number of natural product extracts which may have potential as leads for the development of future therapeutics for hyperlipidemia and related diseases including atherosclerosis.Thu, 28 Aug 2014 15:08:07 GMThttp://hdl.handle.net/2381/290492014-08-28T15:08:07ZIdentifying the vulnerable carotid plaque by means of dynamic ultrasound image analysishttp://hdl.handle.net/2381/29031
Title: Identifying the vulnerable carotid plaque by means of dynamic ultrasound image analysis
Authors: Kanber, Baris
Abstract: Stroke is a global healthcare problem with very high rates of morbidity and mortality;
therefore, early diagnosis and prevention are of paramount importance. Many strokes
are caused by atherosclerotic plaques in the carotid arteries, and these are often
assessed using ultrasound examinations that include the measurement of the degree
of stenosis. However, despite the degree of stenosis being an important clinical
marker of disease severity, there is an urgent need for additional parameters that can
identify high-risk, vulnerable plaques, which may be more likely to cause stroke
regardless of the degree of stenosis.
This thesis describes the development of techniques for measuring plaque
characteristics from ultrasound image sequences, testing the hypothesis that
parameters obtained from these measurements can help identify vulnerable carotid
plaques.
Novel methods to track plaque boundaries in ultrasound image sequences were
developed (Chapters 2 and 3). This allowed the dynamic assessment of plaque
echogenicity (Chapter 3), a novel method of quantifying plaque surface irregularities
(Chapter 4), and the investigation of arterial wall (Chapter 5) and plaque (Chapter 6)
mechanics. In the penultimate chapter (Chapter 7), these parameters were integrated
in the form of a carotid plaque risk index (CPRI) and its efficacy in predicting the
presence of patient symptoms was assessed.
The dynamic measures of plaque echogenicity and the novel plaque surface
irregularity index correlated significantly with the presence of patient symptoms. The
CPRI, which combines these parameters with the degree of stenosis, improved
diagnostic accuracy compared to the degree of stenosis on its own, and led to a better
separation of the symptomatic and asymptomatic patient groups.
The methods for characterising plaque characteristics developed in this thesis could be
valuable for identifying vulnerable carotid plaques. The risk index, if its efficacy is
confirmed in subsequent clinical trials, may help reduce the incidence and burden of
stroke.Fri, 08 Aug 2014 14:00:09 GMThttp://hdl.handle.net/2381/290312014-08-08T14:00:09ZDiurnal variation in excitation-contraction coupling in rat ventricular myocyteshttp://hdl.handle.net/2381/29009
Title: Diurnal variation in excitation-contraction coupling in rat ventricular myocytes
Authors: Collins, Helen Elizabeth
Abstract: Diumal variation has been reported in many cardiovascular haemodynamics parameters
such as heart rate and blood pressure and the cardiac action potential. This variation
may result from the diurnal variation in sympathetic activity or in cardiac gene
expression. However, it is unknown whether these time-of-day dependent changes
impact on excitation-contraction (EC) coupling. There is also a morning peak in the
onset of ventricular arrhythmias and associated sudden cardiac death in man, which
appear linked to the increase in sympathetic activity. Therefore, the aims of this
investigation were to determine whether there was a time-of-day dependent variation in
EC-coupling and its modulation by sympathetic stimulation.
Left ventricular myocytes were isolated during either the resting period (ZT3) or the
active period (ZT15) o f the adult Wistar rat. [Ca[superscript 2+]][subscript i] was determined using Fura-2 and
contraction strength was determined using cell-edge detection in response to electrical
field stimulation, and gene expression was determined using quantitative real-time RT-PCR.
To determine the effects of hypertension-induced hypertrophy, myocytes were
isolated from pre- and post-hypertensive spontaneously hypertensive rats (SHR).
The basal Ca[superscript 2+] transient, contraction strength and SR Ca[superscript 2+] content were significantly
greater in resting period (ZT3) myocytes than active period (ZT15) myocytes. Systolic
[Ca[superscript 2+]], amplitude of Ca[superscript 2+] transient and SR Ca[superscript 2+] content in response to isoproterenol (>
3nM) were significantly greater in resting period (ZT3) myocytes. The percentage of
myocytes developing arrhythmic activity in response to isoproterenol was greater in
resting period (ZT3) myocytes. Nitric oxide synthase (NOS) inhibition using L-NNA
significantly increased systolic [Ca[superscript 2+]], amplitude of Ca[superscript 2+] transient, SR Ca[superscript 2+] content and
the percentage of myocytes developing arrhythmic activity in active period (ZT15)
myocytes thereby depressing time-of-day dependent variation in these parameters. In
addition, expression of NOS1 was significantly greater in active period (ZT15)
myocytes. Diurnal variation in the Ca[superscript 2+] transient and its responsiveness to isoproterenol
were depressed in adult SHR, however, this did not reflect a depression of diurnal
cycling in NOS1 expression.
This shows for the first time a time-of-day dependent variation in the Ca[superscript 2+]-transient and
resulting contraction strength, reflecting levels of SR Ca[superscript 2+]-loading, due to a NOS-signalling
pathway. There was also a reduction in sympathetic-induced arrhythmic
activity in active period (ZT15) myocytes which was associated with increased NOS
activity. Therefore, variation in NOS may be a means of protecting against arrhythmias
during severe sympathetic stimulation. Loss of protection through disruption to the
circadian clock resulting from cardiomyopathies such as hypertension-induced
hypertrophy may result in a decreased threshold for sympathetic-induced arrhythmias,
however; this requires further work to elucidate the underlying molecular mechanisms.Fri, 01 Aug 2014 09:31:28 GMThttp://hdl.handle.net/2381/290092014-08-01T09:31:28ZAn investigation into carotid atherosclerotic plaque instabilityhttp://hdl.handle.net/2381/28979
Title: An investigation into carotid atherosclerotic plaque instability
Authors: Salem, Murtaza Karimjee
Abstract: Stroke is the leading cause of death and permanent neurological disability in the developed
world and a significant burden on the NHS and wider economy. A third of all strokes are
caused by thrombo-embolism from unstable carotid atherosclerotic plaques. The exact
pathogenesis of plaque progression and instability is unknown. The aim of this thesis was to
investigate carotid plaque instability from a clinical perspective and on a molecular level.
Patients with spontaneous embolisation detected during Transcranial Doppler (TCD)
monitoring were significantly more likely to have recent symptoms and recurrent events than
those patients without evidence of spontaneous embolisation. Features of unstable plaque
histology including large lipid core, intra-plaque haemorrhage, plaque inflammation,
neovascularisation and cap rupture all decreased with time since event from 0-28 days but
then increased in prevalence thereafter. Ultrasound features found to be related to unstable
plaques included Grayscale Median (GSM) <25 and plaque area >80mm[superscript 2]. Finally a
predictive model was created to identify patients with a histologically unstable plaque using
clinical and ultrasound parameters.
Using whole-genome wide microarray and results validated using qRT-PCR in an
independent cohort, expression of the CCL19 and CTSG genes were significantly upregulated
in plaques from patients with unstable plaques graded according to 1. Clinical; 2.
Ultrasound; 3. TCD microemboli and 4. Histological criteria.
Using ELISA, serum concentration of CCL19 was significantly higher in patients with
clinically and histologically unstable plaques (p=0.02). Immunohistochemical staining for
CCL19 demonstrated positive staining in histologically and clinically unstable plaques
(P=0.03) with co-localisation to CD3 positive T-cell lymphocytes.
In conclusion there is further evidence that plaque instability is greatest in the hyper and
acute period after symptom onset. CCL19 is significantly over-expressed in patients with
clinically unstable carotid atherosclerotic plaques and warrants further investigation. Clinical
and non-invasive ultrasound imaging criteria can be used to predict the patient with the
unstable plaque.Thu, 10 Jul 2014 15:10:06 GMThttp://hdl.handle.net/2381/289792014-07-10T15:10:06ZValidation of a novel evaluation framework by examination of an audio-visual intervention designed to improve junior doctors’ management of the feverish childhttp://hdl.handle.net/2381/28973
Title: Validation of a novel evaluation framework by examination of an audio-visual intervention designed to improve junior doctors’ management of the feverish child
Authors: Roland, Damian
Abstract: A large amount of resource is expended attempting to change clinical practice; however the effects of these interventions are seldom assessed. A systematic literature review revealed that existing outcome measures to examine the effects of a ‘practice changing intervention’ (patient video cases as the instructional element in an e-learning package) lacked validity. As existing frameworks for the evaluation of practice changing interventions may not adequately determine an interventions’ true effectiveness a novel “7Is framework” was developed. This contains 7 domains: Interaction, Interface, Instruction, Ideation, Integration, Implementation and Improvement.
To produce bespoke outcome measures for the “7Is Framework” domains the following studies were performed:
i) Focus groups with junior doctors demonstrated poor differentiation between concepts of competence and confidence. A new indicator of self-awareness, the perception of “safeness”, was generated (Ideation).
ii) Paediatricians rated quality and acuity of a selection of clips at differing technical qualities to produce gold standard responses for video case questions (Integration).
iii) A novel matrix determining how experience and tacit knowledge may impact on patient outcomes was validated as a measure of behaviour change (Integration).
iv) A time series of presentation and admission rates of feverish children provided outcome data for the evaluation (Implementation / Improvement).
An audio-visual intervention in paediatric fever was designed, delivered and tested against the new system (studying 202 UK doctors). Interaction with the intervention was variable, only 28.7% completed the post learning section and issues were identified with accessing the video cases. Although measures of ideation increased and there was a trend towards behaviour change, full implementation of the guidance did not occur and overall admission rates increased.
The 7Is Framework allows the various effects of an intervention to be conceptualised, promoting the development of a set of valid and specific outcome measures, ultimately leading to more robust evaluation.Thu, 10 Jul 2014 13:01:22 GMThttp://hdl.handle.net/2381/289732014-07-10T13:01:22ZUnderstanding the genetic basis of atrial fibrillation : next steps after genome-wide association studieshttp://hdl.handle.net/2381/28909
Title: Understanding the genetic basis of atrial fibrillation : next steps after genome-wide association studies
Authors: Mahida, Saagar Narendrasinh
Abstract: Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in clinical practice. Over
the past two decades, we have come to appreciate that AF has a significant heritable
component. The recent advent of next-generation sequencing technology has
spawned a new era of research into the genetic basis of AF. Genome-wide association
studies (GWAS) have identified multiple common variants underlying AF. Further,
exome sequencing has emerged as a potentially powerful technique for the
identification of mutations underlying familial forms of AF. In this thesis, we sought to
further elucidate the genetic basis of AF though two specific aims. Firstly, we
investigated the mechanistic link between KCNN3, a potassium channel gene which
was identified in a GWAS for lone AF, and arrhythmia pathogenesis. Secondly, we
performed exome sequencing and classical linkage analysis in two AF pedigrees to
identify novel mutations for the arrhythmia. We demonstrate that overexpression of
Kcnn3 in a murine model results in an increased susceptibility to AF. Interestingly,
these mice also display a high incidence of sudden death due to heart block. Exome
sequencing in an AF pedigree identified a potentially causative mutation in the
transcription factor gene GATA6. In a second AF pedigree, we identified a novel locus
for the arrhythmia on chromosome 1. However the causative mutation at this locus
remains elusive. Ultimately, the identification of the genetic substrate underlying AF is
likely to uncover novel therapeutic targets as well as enhancing risk stratification for
this common and morbid arrhythmia.Fri, 13 Jun 2014 15:40:36 GMThttp://hdl.handle.net/2381/289092014-06-13T15:40:36ZIs dynamic cerebral autoregulation impaired in idiopathic Parkinson’s disease?http://hdl.handle.net/2381/28752
Title: Is dynamic cerebral autoregulation impaired in idiopathic Parkinson’s disease?
Authors: Haunton, Victoria Joanna
Abstract: Background:
Cerebral autoregulation (CA) refers to the ability of the brain to maintain a relatively constant cerebral blood flow (CBF) in response to significant changes in cerebral perfusion pressure. CA is governed by several key mechanisms, which can be described as neurogenic, myogenic and metabolic. Idiopathic Parkinson’s disease (PD) is a common neurodegenerative disease with a significant autonomic component, and it has been hypothesised that CA in PD may therefore be impaired. However, to date, the literature on this subject has been limited in its scope, of uneven quality and has yielded conflicted findings.
Objective:
This Thesis aimed to determine if dynamic CA is impaired in patients with idiopathic PD, compared to healthy control subjects, and if dynamic CA varies between the ‘on’ and ‘off’ states of PD.
Methods:
CA was assessed by means of continuous non-invasive monitoring of arterial blood pressure (BP) and velocities in the middle cerebral arteries bilaterally using transcranial Doppler ultrasound. A cohort of patients with idiopathic Parkinson’s disease were studied in both their clinically ‘on’ and ‘off’ states, and their data were compared to that obtained from age- and sex-matched healthy controls. In addition to assessing the CA response to spontaneous fluctuations in BP, a variety of paradigms were used to induce changes in mean cerebral blood flow velocity and BP, including passive arm movement and hyperventilation.
Results:
This study has demonstrated that CA responses to spontaneous fluctuations in BP do not differ significantly between the on and off states of PD, but do differ significantly between PD patients and healthy controls, ultimately suggesting that CA is altered, but not necessarily impaired, in idiopathic PD. CBF velocity responses to passive arm movement and hyperventilation did not differ significantly between the on and off states of PD, or between PD patients and healthy controls.Fri, 11 Apr 2014 11:56:06 GMThttp://hdl.handle.net/2381/287522014-04-11T11:56:06ZDevelopment of a structured education programme to improve cardiovascular risk in women with polycystic ovary syndromehttp://hdl.handle.net/2381/28638
Title: Development of a structured education programme to improve cardiovascular risk in women with polycystic ovary syndrome
Authors: Mani, Hamidreza
Abstract: Background: Polycystic ovary syndrome (PCOS) is a chronic condition with a reported prevalence of up to 18% and is associated with adverse long term outcomes. Structured education programmes have proved effective at optimising physical activity, biomedical outcomes and well-being of people with chronic conditions, however, pragmatic structured education interventions in women with PCOS are lacking.
Aim: To develop an evidence-based structured education programme for women with PCOS and increase their step-count.
Methods: Using a local multi-ethnic database, phenotypic presentation and long term cardiovascular outcomes of women with PCOS was determined. The attitudes of women with PCOS towards an education programme and their experience of living with PCOS was sought through qualitative interviews. A systematic review compared lifestyle interventions with insulin sensitizers in PCOS. Using the Medical Research Council’s framework, the SUCCESS education programme was developed and tested in a randomised controlled trial.
Key Findings:
• There are phenotypic differences in women with PCOS according to ethnicity or body weight.
• Overweight and obese women with PCOS have a high proportion of cardiovascular risk factors and higher age-specific rates of myocardial infarction as compared to general female population.
• In a meta-analysis, no statistical differences exist between the effect of lifestyle interventions and Metformin on BMI at six month.
• Women with PCOS welcome group education programmes. They have significant body image issues, which has an emotional impact.
• The SUCCESS education programme did not increase the step count at three month.
Conclusion: This project established the high cardiovascular risk associated with PCOS. Although, the SUCCESS education programme did not show positive results at three months, it is the first pragmatic structured education programme tailored to women with PCOS. Outcomes at the final analysis in 12 months, will inform whether the programme should be implemented or adapted further and re-evaluated.
Description: Due to copyright restrictions the published articles have been removed from appendix 6.1 and 6.2 of the electronic version of this thesis. The unabridged version can be consulted, on request, at the University of Leicester’s David Wilson Library.Thu, 06 Mar 2014 15:53:10 GMThttp://hdl.handle.net/2381/286382014-03-06T15:53:10Z